1. Field of the Invention
The present invention relates to a connecting rod for a reciprocating internal combustion engine in which the effective length of the connecting rod may be controllably varied so as to change the compression ratio of the engine.
2. Disclosure Information
Students of thermodynamics understand that, in general, higher compression ratios yield higher thermal efficiency for piston-type internal combustion engines. Unfortunately, with premixed charge engines, most commonly sold in the form of spark-ignited engines operated on gasoline, higher compression ratios may cause problems arising from pre-ignition. This problem may be exacerbated, moreover, when an engine is turbocharged or super-charged. Therefore, it would be desirable to have an engine which can normally be operated at a higher compression ratio at most operating conditions, so as to yield maximum fuel economy, while still allowing operation at lower compression ratio at the highest power conditions. This would allow the engine to produce maximum power without knock or preignition. The inventor of the present connecting rod has provided a unique solution to problems associated with known variable compression ratio arrangements. Such arrangements as pistons with variable compression height, typically developed by BICERI, as well as a variable plethora of other mechanical devices all suffer from problems relating to controllability, inadequate time response, excessive weight, excessive complexity, and other issues. The present connecting rod solves the problems associated with prior compression ratio controlling devices by using a mechanism which starts with a four-bar linkage extending between the large and small ends of the connecting rod and which utilizes inertia forces to obtain the required compression ratio changes, while employing a locking mechanism which need only withstand the buckling forces imposed upon the four-bar link mechanism to maintain the connecting rod at the selected compression ratio.